1. Technical Field
The present invention relates to a computer system capable of displaying a display power management signaling (DPMS) mode and, more particularly, to a power management system device for a method of displaying the DPMS mode in which, when the computer system is not manipulated for a predetermined time, i.e., while not being used, the system converts to a first power save mode, generates a message and waits for user feedback, thus reducing power consumption.
2. Related Art
Contemporary computer systems generally consist of a main unit (which may have built-in storage devices such as floppy disks, hard disks and CD-ROM), a keyboard and a monitor. The main unit may be connected to a printer and other peripheral devices. In normal usage, it is common for the monitor and other peripherals to be turned on and to remain on for as long as the computer is running, even though the peripherals are actually used only a small percentage of the time. A typical color video monitor, for example, may consume as such as 50 to 80 percent of the total 5 electrical energy consumed by a personal computer (PC). If the monitor consumes valuable energy only to remain idle, not only the valuable energy resources will be wasted but the life of the monitor will decrease rapidly. Obviously, power can be conserved if the user turn the computer system off or in a standby mode each time the computer system is no longer in use for an extended period. This requirement is, however, impractical. Therefore, system should be designed to automatically conserve valuable energy resources when the computer system is not in use.
In principle, automatically saving energy by turning off the computer system is fairly easy. Portable computers such as laptop computers are invariably designed so that if there is no activity from the keyboard or from other external inputs during a specified time, the computer systems are turned off or placed in a standby mode to save energy. Only minimal logic is kept active to detect when the keyboard or other external inputs are becoming active again so as to turn the computer system back on. In portable computers, this power saving feature is fairly simple to implement, since the monitor display is integrated with the computer system. However, for normal desktop personal computers in which a monitor is physically separated from the main computer unit, turning off the external monitor automatically from the main computer unit is much more difficult because most monitor systems contain no special lines or special commands to turn the power on or off.
Conventional power saving features for typical personal computers having monitors as separate items are disclosed, for example, in U.S. Pat. No. 5,059,961 for Screen Blanker For A Monitor Of A Computer System issued to Cheng, U.S. Pat. No. 5,163,124 for Method And Apparatus For Controlling Power To Device In A Computer System issued to Yabe et al., U.S. Pat. No. 5,335,168 for Computer System With Power-Down Mode For Monitor issued to Walker, U.S. Pat. No. 5,375,245 for Apparatus For Automatically Reducing The Power Consumption Of A CRT Computer Monitor issued to Solhjell et al., U.S. Pat. No. 5,384,721 for Information Processing System With A Power Control Unit issued to Joto, U.S. Pat. No. 5,389,952 for Low-Power-Consumption Monitor Standby System issued to Kikinis, U.S. Pat. No. 5,408,668 for Method And Apparatus For Controlling The Provision Of Power To Computer Peripherals issued to Tornai, U.S. Pat. No. 5,481,732 for CRT Monitor Power Control Unit issued to Shahbazi, and recent U.S. Pat. No. 5,483,464 for Power Saving Apparatus For Use In Peripheral Equipment Of A Computer issued to Song and assigned to the same assignee of the present invention. Usually, the monitor is shut down during the period of inactivity with the exception of a small amount of power necessary to detect when the computer system becomes active again so as to resume operation of the monitor. Generally, when the monitor is powered normally, the display of data image is blanked during the period of inactivity and re-displayed when the computer system becomes active, i.e., when an input device such as a keyboard is operated. During this type of blanking, however, the monitor continues to consume normal power.
Accordingly, display power management signaling (DPMS) mode standards have been set to save power consumption by controlling monitor power with respect to the operational status of the computer system. In the DPMS mode, power supply is managed according to the operational status of the computer system. The mode status of the power management is classified into ON, STAND-BY, SUSPEND and OFF, which are represented here in operational sequence. The horizontal and vertical sync signals are applied according to the respective power management states as listed in the below table.
______________________________________ SYNC SIGNAL POWER MANAGEMENT STATUS HORIZONTAL VERTICAL ______________________________________ ON MODE .smallcircle. .smallcircle. STAND-BY MODE x .smallcircle. SUSPEND MODE .smallcircle. x OFF MODE x x ______________________________________
In the table ".smallcircle." indicates the presence of a sync signal, determined as a horizontal sync signal frequency higher than 10 kHz and a vertical sync signal frequency higher than 40 kHz; and ".times." indicates that the respective sync signals are below these frequencies and therefore determined to be interrupted. The duty ratio of the sync pulses is assumed less than 25%. When the DPMS mode is activated, however, the monitor is blanked, and may be left powered-on for a long period of time. If the power-off state is incorrectly assumed by the user who leaves the display in an "off" state. This is contrary to the basic function of the power save mode of the computer system which fails to effectively save power.